musicxml | MusicXML specification | Development Tools library

I have written a python script to process midi files with music21 and write again a midi file. This works if the solo piano is "simple" in the sense, that there are not multiple pitches / notes played simultaneously in a voice.

https://github.com/githubuser1983/algorithmic_python_music/blob/main/12RootOf2.py

The relevant part from above is:

I am currently working on a sight-reading app that requires display of musical notation; I am struggling to find a way to efficiently draw this in a JFrame.

I am looking at the JFugue library to help with this, and the description of the class MusicXMLParser_J states the following.

Parses a MusicXML file, and fires events for ParserListener interfaces when tokens are interpreted. The ParserListener does intelligent things with the resulting events, such as create music, draw sheet music, or transform the data. MusicXmlParser.parse can be called with a file name, File, InputStream, or Reader.

However, I am not certain which class that implements ParserListener would allow the drawing of sheet music. Any help is greatly appreciated.

As we know, in JavaScript, we can freeze an object in runtime such that it will be immutable, furthermore, we can recursively freeze its mutable members such that it can no longer be modified from now on. Is it possible to achieve similar thing in C++?

I am aware of that this will inevitably cause an overhead and I am OK with it. My biggest problem is my class will have public members, and it looks like there is no way to stop a non-const reference owner from changing a public member directly.

EDIT: I am going to describe the design problem I am facing and suggest some solution.

We want to parse a musical sheet (in MusicXML form) into our internal hierarchical data structure, after this, our business logic will use the data structures and retrieve needed info from it. Our internal data structure needn't and shouldn't be modified after the parsing procedure. Because parsing procedure is pretty complex, we cannot make everything const and we have to modify the object after creation, so the "freezing" idea is natural here to prevent unintended modification to our DS.

Some ideas I have:

1. Spam getters and setters in my classes, and add a freezed flag for every class. (Most straightforward, but not tidy.)
2. Use some accessor helper classes to achieve this read only limitation.
3. It is too complex, and it is not worthwhile to freeze the objects.

I've noticed and issue when trying to assemble sequential and parallel chords in music21 toolkit.

I am reading in the following XML as a text file in R: